This invention relates generally to an improved battery pack for use in short term battery powered operation of a medical instrument, such as an infusion pump of the type used to deliver selected fluids to a patient according to a prescribed time schedule. More particularly, this invention relates to a compact battery pack having one or more rechargeable batteries mounted permanently and substantially inaccessibly therein.
Modern medical treatment facilities utilize a variety of relatively sophisticated electronic instruments in the course of patient diagnosis and treatment. As one common example, electronic fluid infusion instruments are commonly used for administering one or more selected medical fluids to a patient at a prescribed flow rate and time schedule. Such fluid infusion and other electronic equipment require a source of electrical power to maintain the medical instrument in a desired operational state. In this regard, such medical instruments are normally designed to operate on conventional 120 volt AC power and include appropriate power cords for plug-in connection to a standard household power supply.
Alternatively, in some cases, the medical instrument is designed to operate on a DC power supply which is obtained by connecting an appropriate transformer to a standard household power supply. In this latter case, medical instruments have been provided with internal transformers integrated directly into the instrument housing, or an external transformer adapted for direct plug-in connection to a power supply outlet.
While electrically-powered medical instruments have significantly enhanced medical diagnosis and treatment, it is often necessary for an electronic instrument to be disconnected from its regular power source to permit patient and/or instrument movement from one location to another within a medical facility. In this regard, some medical instruments have been designed for relatively short term battery operation to accommodate continuous instrument operation as the patient and instrument are moved.
In such devices, the battery power source has normally been integrated directly into the housing of the medical instrument, frequently in association with an on-board charger designed to maintain the battery source in a recharged state when the instrument is connected to the normal AC power supply. However, such arrangements have not safeguarded against unauthorized replacement of the battery source with cheaper and potentially inferior batteries. Moreover, such prior arrangements have not effectively isolated the electronic components of the medical instrument from potentially explosive gases which are sometimes generated in the event of battery malfunction.
There exists, therefore, a significant need for improvements in integrating a battery power source with a medical instrument for short term instrument operation, particularly wherein the battery source is easily accessed for replacement with fresh batteries, when necessary. Moreover, there exists a need for providing a high quality battery power source wherein the use of potentially inferior batteries is effectively prevented. Still further, there exists a need for providing a short term battery power source in a medical instrument, wherein the battery source is effectively isolated from electronic components of the medical instrument. The present invention fulfills these needs and provides further related advantages.